Janusz Stanislaw Wilczynski

High-speed signal propagation on lossy transmission lines

This paper addresses some of the problems encountered in propagating high-speed signals on lossy transmission lines encountered in high-performance computers. A technique is described for including frequency-dependent losses, such as skin effect and dielectric dispersion, in transmission line analyses. The disjoint group of available tools is brought together, and their relevance to the propagation of high-speed pulses in digital circuit applications is explained. Guidelines are given for different interconnection technologies to indicate where the onset of severe dispersion takes place. Experimental structures have been built and tested, and this paper reports on their electrical performance and demonstrates the agreement between measured data and waveforms derived from analysis. The paper addresses the problems found on lossy lines, such as reflections, rise-time slowdown, increased delay, attenuation, and crosstalk, and suggests methods for controlling these effects in order to maintain distortion-free propagation of high-speed signals.

Imaging performance of multilayer X-ray mirrors

We analyze soft x‐ray images of the solar corona, obtained on the day of the solar eclipse in July 1991, and find that the deviations of our telescope mirror from the perfect surface are less than 1 A for spatial periods between 1 μm and 1 mm. Our thin film deposition technique allows us to reduce errors over larger periods to the 1 A level. Thus, we are able to produce large (diameter over 20 cm) x‐ray mirrors with diffraction limited resolution below 0.01 arcsec.

Design And Assembly Of A High Resolution Schwarzschild Microscope For Soft X Rays

Recently developed multilayer coatings permit use of normal incidence optics for soft x-rays promising a resolution that should be substantially better than that obtained with grazing incidence optics. We describe the design and assembly of a Schwarzschild objective for a scanning x-ray microscope. The Schwarzschild objective, consisting of two nearly concentric spherical mirrors promises diffraction-limited resolution for soft x-rays.© (1982) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Normal incidence soft x-ray telescopes

Photos obtained during 5 mm of observation time from the flight of our 25-cm-diam normal-incidence soft x-ray (λ = 63.5 a) telescope on September 11, 1989, are analyzed and the data are compared to the results expected from tests of the mirror surfaces. These tests cover a range of spatial periods from 25 cm to 1 a. The photos demonstrate a resolution close to the photon shot noise limit and a reduction in the scattering of the multilayer mirror compared to a single surface for scattering angles above 1 arcmin, corresponding to surface irregularities with spatial penods below 10 μm. Our results are used to predict the possible performance of future telescopes: We conclude that sounding rocket observations might be able to reach a resolution around 0.1 arcsec. Higher resolutions will require flights of longer durations and improvements in mirror testing for the largest spatial periods.

Fabrication and performance studies of multilayer polymer/metal interconnect structures for packaging applications

Multilayer copper/polyimide interconnect structures were fabricated using a reactive-ion-etching-based lift-off technique. Conductor cross-sectional area control, planarity, and a gap-free structure were made possible by the use of a novel siloxane-polyimide. The resultant structure consisted of two signal wiring layers between two ground planes with a nominal impedance of 40 Omega . Although redundant metallization processes were found to repair open lines, they resulted in an increase of the number of processing steps and could result in an increase of defects. Stud chain structures were found to survive cooling to 77 K with very little change in their characteristics, while heating of the copper interconnections to 350 degrees C in a reducing environment reduced their resistance by 3%.<<ETX>>

Construction Of A Multilayered X-Ray Telescope For Solar Coronal Studies From Space

We discuss the construction and flight of an ultrahigh resolution soft x-ray telescope which is to be flown on a NASA sounding rocket in 1986. The possibility of using normal incidence figured optics allows the construction of x-ray mirrors which, on a cost-for-cost basis, have an order of magnitude higher spatial resolution than do grazing-incidence mirrors. For the past two years our groups at the Smithsonian Astrophysical Observatory and the IBM Watson Research Center have been collaborating on x-ray multilayer testing (along with R. Bartlett of Los Alamos National Laboratory) and on the design and construction of a Ritchey-Chretien telescope. The initial use of this instrument will be to study the solar x-ray corona at very high spatial resolution; future uses will include simultane-ous high resolution imaging and spectroscopy and soft x-ray/XUV astronomy. The engineering requirements for flying this instrument on a sounding rocket are substan-tial and we will discuss the specialized design problems which have had to be overcome. The optical design parameters call for performance which exceeds the visible-light diffraction limit, while the multilayer coatings for soft x-ray wavelengths require substrate surface finish of the highest quality. We will also discuss some of the future astrophysical applications of the technique and some of the possible instruments which may be flown in the next few years.

The Optomechanical Design and Operation of the Ionospheric Mapping and Geocoronal Experiment

The Ionospheric Mapping and Geocoronal Experiment (IMAGER) is a space-based, multispectral, imaging payload, designed at the U.S. Naval Research Laboratory. The IMAGERs primary science mission is to find, track, and measure ionospheric irregularities as they move across the surface of the Earth and vary with time. IMAGER will observe the ionosphere of the Earth in narrow extreme- and far-ultraviolet passbands centered at 83.4, 130.4, 135.6, and 143.0 nm. These emissions are produced by naturally occurring airglow emission from the nighttime and daytime ionosphere and thermosphere. The IMAGER consists of an imaging telescope with a filter wheel assembly and a pair of microchannel plate-based imaging detectors with cross delay line readouts. The telescope of the instrument consists of a 160 mm diameter, F/4.0 off-axis very fast aplanatic Gregorian telescope. The focal length is 640 mm and the field of view is 1.6° × 1.6° which will cover approximately 1000 × 1000 km2 on the Earths surface. The modulation transfer function is above 0.90 at 2.8 line pairs-millimeter-1 over the field, which corresponds to a line pair separated by 20 km on the Earth. The spatial resolution is approximately 10 × 10 km2 and is oversampled by a factor of 9 (3 × 3 pixels per resolution element). A system of reflective filters is used to select different wavelengths of interest. The telescope will be gimbaled to provide a field-of-regard encompassing the entire disk and limb of the Earth. The gimbal will also allow the telescope to track the ionospheric irregularities as they move. This paper describes the design of the optical and mechanical systems and their intended performance and includes an overview of the mission and science requirements that defined the aforementioned systems.

New Polarization Interferometer for Fourier Analysis

A generator of fringes of variable frequency is described as consisting of only two Wollaston prisms W1 and W2 with attached polarizers P1 and P2. A properly oriented half-wave plate H1 is situated between W1 and W2. When the two Wollaston prisms are counterrotated by an equal angle ϕ about an axis joining the geometrical centers of their faces, fringes appear of variable frequency f=4(Ne − N0) tanα cosϕ, where α is the angle of the prisms, Ne and N0 are the principal indices. When the fringe pattern is projected by a demagnifying microscope lens, the contrast remains constant up to 280 lines/mm.

Factors affecting the interconnection resistance and yield in the fabrication of multilayer polyimide/metal thin film structures

The use of a lift-off technique to fabricate a high-density structure consisting of multiple layers of metal/polyimide thin film structure on a silicon substrate is described. To achieve better performance and high yield, the authors evaluated the process design, the processing parameters, and the thickness of the Cr/Cu/Cr metallurgy, along with the use of suitable polyimide dielectrics. The plasma processing conditions, the types of passivation metals on Cu, and the use of a siloxane-polyimide as the gap-fill etch-stop material were all shown to play a very critical role in affecting the interconnection resistance and yield of the multilayer thin film structures. By optimizing these parameters the feasibility of fabricating high-density thin film wiring layers with good yield is demonstrated.<<ETX>>

Imaging performance and tests of soft x-ray telescopes

Photos obtained during 5 mm. of observation time from the flight of our 10 inch normal incidence soft x-ray (1 = 63.5A) telescope on September 11, 1989 are analyzed and the data are compared to the results expected from tests of the mirror surfaces. These tests cover a range of spatial periods from 25 cm to lÅ. The photos demonstrate a reduction in the scattering of the multilayer mirror compared to a single surface for scattering angles above 1 arcmin, corresponding to surface irregularities with spatial periods below 10 tim. Our results are used to predict the possible performance of future flights. Sounding rocket observations might be able to reach a resolution around 0. 1 arcsec. Higher resolutions will require flights of longer durations and improvements in mirror testing for the largest spatial penods.